{\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\begin{tabular}{l*{4}{c}}
\hline\hline
&\textbf{Group 1}&\textbf{Group 2}&\textbf{Diff.} &\textbf{p-val}\\
& (1) & (2) & (3) & (4)\\
\hline
Gender (1 = Male, 2 = Female) &  34.26 &  32.30 &   1.96 &   0.00 \\
& (8.23) & (8.20) & & \\
Country (1 = US, 2 = India) &  32.00 &  35.21 &  -3.22 &   0.00 \\
& (8.49) & (8.85) & & \\
Age (1 = Under 33, 2 = Over 33) &  33.42 &  31.78 &   1.64 &   0.00 \\
& (8.84) & (8.83) & & \\
\hline\hline
\end{tabular}}
